Endoscope-assisted Anterior Cervical Discectomy and Fusion for the Treatment of Cervical Spondylotic Myelopathy

Résumé

We describe a minimally invasive surgery using Endoscope-assisted Anterior Cervical Discectomy and Fusion for the Cervical Spondylotic Myelopathy.

Résumé

Cervical spondylotic myelopathy (CSM) is a common cause of cervical spinal cord disease. Spinal endoscopy offers surgical advantages such as a magnified view and a water-mediated clear surgical field. This study describes an endoscope-assisted anterior cervical discectomy and fusion (ACDF) procedure. The addition of spinal endoscopy to traditional ACDF surgery magnifies the surgical field and allows for more precise operations, thereby improving surgical safety. Postoperatively, patients experienced significant improvements in neurological function, with no complications such as dysphagia, hematoma, or spinal cord injury. Postoperative imaging revealed that spinal cord compression was completely relieved, with sufficient decompression of the spinal cord and optimal placement of the fusion cage. The clear visual field provided by spinal endoscopy improves the identification of cervical anatomical structures during surgery, effectively reducing the risk of injury to the spinal cord and nerves. Endoscope-assisted ACDF has demonstrated excellent clinical and radiological outcomes in the treatment of CSM.

Introduction

Cervical spondylotic myelopathy (CSM) is one of the more severe forms of cervical spondylosis. CSM is a group of syndromes caused by degenerative changes in the cervical spine, leading to degeneration of the surrounding structures such as intervertebral discs and ligaments. These structures subsequently compress the spinal cord, resulting in limb dysfunction or even paralysis. Early diagnosis and timely intervention are critical for improving patient prognosis. Surgical intervention is often required when conservative treatments fail or spinal cord dysfunction worsens^1,2.

Several surgical options are available for the treatment of cervical spondylotic myelopathy (CSM), including traditional anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF), cervical disc replacement (CDR), and hybrid surgery (HS), which combines ACDF and CDR³. Traditional anterior cervical discectomy and fusion (ACDF) is a common treatment approach for CSM that effectively alleviates symptoms by directly decompressing the spinal cord and nerve roots. However, this traditional surgery has limitations, including a narrow surgical field and challenges with intraoperative hemostasis. These issues are particularly pronounced in patients with ossification of the posterior longitudinal ligament (OPLL), which prevents the compressive material from being completely removed during surgery and substantially elevates the risk of spinal cord injury^4,5,6. In 1983, Bollati reported 57 anterior cervical surgeries performed with the assistance of a microscope; these patients demonstrated substantially reduced postoperative complications and increased safety and efficacy⁷. Compared with traditional ACDF, microsurgical techniques offer certain advantages; however, challenges such as insufficient precision, poor hand-eye coordination, and blind spots in the surgical field are still present, limiting the clinical application of these techniques⁸.

Spinal endoscopic surgical techniques, characterized by greater visual clarity, excellent tissue identification, and operational flexibility, have been widely applied in lumbar spine surgeries and have achieved favorable clinical outcomes^9,10,11. Therefore, we integrated spinal endoscopic techniques with traditional ACDF to thoroughly remove ossification or free nucleus pulposus tissue located anterior to the spinal cord under the clear surgical field provided by the spinal endoscope. This approach eliminates blind spots associated with traditional surgeries and substantially reduces the risk of intraoperative spinal cord injury. This article aims to introduce the key technical aspects of endoscope-assisted ACDF. As traditional ACDF surgery has been extensively described in previous studies¹², it will not be reiterated in this paper.

Protocole

This study was approved by the Ethics Committee of Hebei General Hospital. Informed consent was obtained from all individual participants.

1. Preoperative preparation

1. Before surgery, place the patient in a supine position on the hospital bed, with soft pillows under both shoulders and a cylindrical pillow under the occiput to maintain the cervical spine in a hyperextended position.
   NOTE: This step serves two purposes: (1) to allow the patient to adapt to the surgical position and (2) to assess, while the patient was awake, whether hyperextension aggravates any neurological symptoms.
2. Operation planning on the image: Acquire preoperative computed tomography (CT) with sagittal and coronal reconstructions to detect ossification of the posterior longitudinal ligament (OPLL). Perform magnetic resonance imaging (MRI) to evaluate preoperative spinal cord compression.
   NOTE: The distance of ossification on sagittal CT images can aid in determining the upper and lower ranges of the window.

2. Skin marking and anesthesia

1. Place the patient in a supine position on the operating table, and make skin markings at the surgical segment.
2. Disinfect the surgical site by applying iodine applied twice and followed by a single application of 75% alcohol, using a circular motion from the incision site outward. Plan the incision as a transverse incision on the right anterior neck.
   1. The surgical disinfection range primarily covers the anterior neck and upper chest. Ensure that, vertically, it extends from the inferior border of the mandible to the superior border of the sternum and clavicle, and horizontally, it reaches the lateral borders of the sternocleidomastoid muscles on both sides.
3. Administer preoxygenation using a 5 L/min pure oxygen face mask for at least 3 min to maintain a pulse oxygen saturation of 100% before initiating general anesthesia induction. Have a single anesthesiologist intravenously administer sufentanil citrate injection (0.3-0.5 µg/kg), cisatracurium besylate for injection (0.15-0.20 mg/kg), and etomidate injection (0.2-0.4 mg/kg), while continuous monitoring the electrocardiogram (ECG), blood pressure, and oxygen saturation to ensure intraoperative safety.

3. Exposure of the affected segment

1. Make a transverse incision approximately 3 cm in length on the right anterior neck (Figure 1).
2. Using the Smith-Robinson approach, expose the anterior aspect of the cervical vertebral body and intervertebral disc¹². Use intraoperative C-arm fluoroscopy to confirm the target disc space.
3. Incise the annulus fibrosus of the affected segment, and gradually remove the intervertebral disc and cartilage endplates until the posterior margin of the vertebral body is reached.
4. Install a Caspar retractor, and insert the spinal endoscope system into the intervertebral space (Figure 2).

4. Endoscopic procedures for the cervical spine

1. Under spinal endoscopic visualization, address bony spurs at the posterior margin of the cervical vertebral body, and enlarge the intervertebral space. Use a burr to remove the upper and lower bony spurs as well as the attachment points of the annulus fibrosus.
   1. The range of bony removal on both sides extends to the uncovertebral joints; determine the extent of cranial and caudal excision on the basis of the location and size of the ossification observed on preoperative imaging, ensuring sufficient excision at both ends.
   2. Excise the deep annulus fibrosus. Use nucleus pulposus forceps, Kerrison punches, and other tools alternately to decompress the spinal canal, progressively extending the decompression toward the spinal cord (Figure 3).
      NOTE: During the burring process, lateral grinding and upward traction grinding techniques were prioritized to avoid excessive removal of superficial bone, thereby protecting the bony endplate. The use of a spinal endoscope with a 30° angle, tilting capability, and multidirectional burr further expanded the decompression range and ensured greater surgical precision.
2. Incise the soft the posterior longitudinal ligament (PLL) to expose the spinal cord. After the annulus fibrosus and the superficial layer of the PLL are incised, use a Kerrison punch and a hook knife to cut through the soft PLL and separate the space between the PLL and the spinal cord (Figure 4).
   NOTE: Once the gap between the spinal cord and the PLL are separated, subsequent decompression becomes significantly easier. PLL removal and spinal cord exposure are critical steps in this procedure.
3. For patients with OPLL, begin the procedure with the removal of the soft PLL and exposure of the spinal cord. Use a nerve root dissector to assess the space between the ossification and the spinal cord to confirm whether there is adhesion between the ossification and the dura mater. Use a 45° nucleus pulposus forceps or Kerrison punch to gradually remove the ossified ligament until the dura mater is fully exposed. Perform endoscopic visualization to check if the pulsation of the dura mater is satisfactory (Figure 5).
   NOTE: During this process, a burr, nerve root dissector, nucleus pulposus forceps, or Kerrison punch were used alternately to increase operational flexibility and safety.
4. Use bipolar electrocoagulation probes for hemostasis, and apply fluid gelatin to assist in controlling bleeding. Once the surgical field is confirmed to be free of active bleeding, slowly withdraw the spinal endoscope (Figure 6).
   NOTE: Avoid rapid removal of the spinal endoscope to prevent dural herniation caused by negative pressure.
5. Fill a properly sized titanium mesh cage with autologous bone and insert it into the intervertebral space. Select a titanium plate long enough to cover the surgical segment, and implant six screws into the vertebrae to secure the titanium plate, following the standard procedure of traditional ACDF¹² to ensure postoperative stability and successful fusion.

5. Postoperative care

1. Perform continuous ECG monitoring and administer intermittent oxygen inhalation and nebulization; encourage the patient to cough and expectorate.
2. Assess the patient's pain intensity by inquiry and administer nonsteroidal analgesics promptly as needed.
3. Closely monitor changes in limb muscle strength and sensory function.
4. Remove the drainage tube when the drainage volume is less than 30 mL within 24 h postoperatively.

Résultats

This study included 20 patients who underwent endoscope-assisted ACDF surgery from January 2024 to November 2024. The average age was 62.2 years, and the study sample included 9 females and 11 males. The average operative time was 125.5 min, and the mean volume of blood loss was 59.0 mL (Table 1 and Table 2). All patients achieved successful relief of spinal cord symptoms, with lower postoperative visual analog scale (VAS) scores compared with the preoperative scores and significantly im...

Discussion

Anterior cervical discectomy and fusion (ACDF) is a common surgical method for treating cervical spondylotic myelopathy (CSM) and has satisfactory clinical outcomes^13,14. However, traditional surgery faces challenges such as a limited surgical field and difficulties with hemostasis. These problems are particularly pronounced in cases of ossification of the posterior longitudinal ligament (OPLL) or distant disc herniation; in these cases, the compressive material ...

matériels

Name	Company	Catalog Number	Comments
75% alcohol	Hebei Ruihe Medical Equipment Co., Ltd	CC-01A	PEEK
Anterior Cervical Nail Plate Fixation System	Hebei Ruihe Medical Equipment Co., Ltd	PN-03	Plate:TA3G, Nail:TC4
Cervical Fusion Cage
cisatracurium besylate	SPINENDOS GmbH	SP081430.030	Inner diameter:4.3 mm; Outer diameter:7.0 mm; Field angle: 80 °; Visual angle: 30 °; Working length: 181 mm
Endoscope system	SPINENDOS GmbH	SP082628.351	Φ2.5 mm × 310 mm
Endoscopic forceps	SPINENDOS GmbH	SP082700.040L	Φ4.0 mm × 360 mm
Endoscopic hook	XIYI	MQZ	Φ3.2 mm × 328 mm
Endoscopic rongeur	ELLIQUENCE	DTF-40	40 cm
etomidate	SPINENDOS GmbH	SP082781.835	Φ2.5 mm × 330 mm
High-speed burr	Neusoft Corporation
Interventional radiology	Ferrosan Medical Devices A/S	MS0010
iodine	Sichuan Guona Technology Co.,LTD	NNBP/40D/
Neusoft PACS/RIS	Elliquence, LLC	DTF-40
n-HA/PA66	SPINENDOS GmbH	SP082615.265	Φ7.2 mm × 178 mm
sufentanil citrate injection
SURGIFLO Haemostatic Matrix
Trigger-Flex Bipolar System
Working sheath